U.S. patent application number 11/230694 was filed with the patent office on 2007-03-22 for reduced pressure drop coalescer.
Invention is credited to Eric A. Janikowski, Kwok-Lam Ng, Eric J. Rego, Brian W. Schwandt, Barry M. Verdegan.
Application Number | 20070062886 11/230694 |
Document ID | / |
Family ID | 37882999 |
Filed Date | 2007-03-22 |
United States Patent
Application |
20070062886 |
Kind Code |
A1 |
Rego; Eric J. ; et
al. |
March 22, 2007 |
Reduced pressure drop coalescer
Abstract
A coalescer includes fibrous media capturing droplets of the
dispersed phase, coalescingly growing the droplets into larger
drops which further coalesce and grow to form pools that drain, and
adapted to reduce pressure drop thereacross by increasing dispersed
phase drainage therefrom.
Inventors: |
Rego; Eric J.; (Verona,
WI) ; Schwandt; Brian W.; (Fort Atkinson, WI)
; Janikowski; Eric A.; (Jefferson, WI) ; Verdegan;
Barry M.; (Stoughton, WI) ; Ng; Kwok-Lam;
(Madison, WI) |
Correspondence
Address: |
ANDRUS, SCEALES, STARKE & SAWALL, LLP
100 EAST WISCONSIN AVENUE, SUITE 1100
MILWAUKEE
WI
53202
US
|
Family ID: |
37882999 |
Appl. No.: |
11/230694 |
Filed: |
September 20, 2005 |
Current U.S.
Class: |
210/799 |
Current CPC
Class: |
B01D 17/045
20130101 |
Class at
Publication: |
210/799 |
International
Class: |
B01D 17/02 20060101
B01D017/02 |
Claims
1. A coalescer for coalescing a medium having two immiscible
phases, namely a continuous phase and a dispersed phase, said
continuous phase flowing from upstream to downstream, said
coalescer comprising fibrous media capturing droplets of said
dispersed phase, coalescingly growing said droplets into larger
drops which further coalesce and grow to form pools that drain,
said fibrous media being adapted to reduce pressure drop
thereacross by increasing dispersed phase drainage therefrom.
2. The coalescer according to claim 1 wherein said coalescer has a
first cross-sectional area along a first horizontal plane, and a
second cross-sectional area along a second horizontal plane, said
second horizontal plane being vertically below said first
horizontal plane, said second cross-sectional area being less than
said first cross-sectional area.
3. The coalescer according to claim 2 wherein said coalescer has a
perimeter defining a given shape in a vertical plane, said
perimeter having a plurality of chords thereacross, including
vertical chords and horizontal chords.
4. The coalescer according to claim 3 wherein the longest of said
chords extends vertically.
5. The coalescer according to claim 3 wherein said given shape in
said vertical plane is selected from the group consisting of a
racetrack shape, an oval shape, a triangle shape, a square shape, a
trapezoid shape, and a circle shape.
6. The coalescer according to claim 3 wherein said given shape in
said vertical plane has a hollow interior.
7. The coalescer according to claim 6 wherein flow direction is
selected from the group consisting of: inside-out, namely from said
hollow interior outwardly through said fibrous media; and
outside-in, namely inwardly through said fibrous media into said
hollow interior.
8. The coalescer according to claim 1 wherein said fibrous media
comprises a plurality of fibers having a nonrandom dominantly
vertical orientation.
9. The coalescer according to claim 8 wherein said coalescer has a
perimeter, and said fibers extend dominantly circumferentially
tangentially along said perimeter.
10. The coalescer according to claim 9 wherein said perimeter
defines a given shape in a vertical plane, said perimeter having a
plurality of chords thereacross, the longest of said chords
extending vertically, said fibers extending dominantly
circumferentially tangentially along said perimeter being
dominantly vertical and providing increasing drainage pressure at
lower vertical regions of said coalescer.
11. The coalescer according to claim 10 wherein said coalescer has
a first cross-sectional area along a first horizontal plane, and a
second cross-sectional area along a second horizontal plane, said
second horizontal plane being vertically below said first
horizontal plane, said second cross-sectional area being less than
said first cross-sectional area, said plurality of chords include
vertical chords and horizontal chords, said horizontal chords
including a first horizontal chord along said first horizontal
plane, and a second horizontal chord along said second horizontal
plane, said second horizontal chord being shorter than said first
horizontal chord.
12. The coalescer according to claim 8 comprising a shaker
vertically vibrating said coalescer.
13. The coalescer according to claim 1 wherein said coalescer has a
lower region of greater dispersed phase saturation and smaller
volume than an upper region, to minimize the volume of said fibrous
media where restriction is greatest and continuous phase flow rate
least, and to maximize the volume of said fibrous media where
restriction is least and continuous phase flow rate greatest.
14. The coalescer according to claim 1 wherein said coalescer has a
lower region of increased dispersed phase saturation, and
comprising a lower media element of greater dispersed phase
wettability than said fibrous media and in contact with said lower
region of said coalescer and wicking said coalesced drops from said
fibrous media at said lower region.
15. The coalescer according to claim 14 wherein said fibrous media
is nonwetting with respect to said dispersed phase, and said lower
media element is wetting with respect to said dispersed phase.
16. The coalescer according to claim 1 wherein said coalescer has a
lower region, and comprising a lower media element in contact with
said lower region of said coalescer, and wherein the cosine of the
dispersed phase contact angle of said lower media element is
greater than the cosine of the dispersed phase contact angle of
said fibrous media.
17. The coalescer according to claim 1 wherein said fibrous media
comprises a plurality of fibers having a dominant fiber orientation
angle .alpha. defined as the angle of fiber extension relative to
horizontal, and wherein .alpha. is less than 0.degree. and greater
than minus 90.degree..
18. The coalescer according to claim 1 wherein said fibrous media
comprises a plurality of fibers having a dominant fiber orientation
angle .beta. defined as the angle of fiber extension relative to
flow direction, and wherein .beta. is less than 60.degree. and
greater than minus 60.degree..
19. The coalescer according to claim 1 wherein: said fibrous media
comprises a plurality of fibers having a first dominant fiber
orientation angle .alpha. defined as the angle of fiber extension
relative to horizontal; said plurality of fibers have a second
dominant fiber orientation angle .beta. defined as the angle of
fiber extension relative to flow direction; wherein in combination
.alpha. is less than 0.degree. and greater than or equal to minus
90.degree., and .beta. is less than 60.degree. and greater than
minus 60.degree..
20. The coalescer according to claim 1 comprising a plurality of
localized pockets formed in said fibrous media, said pockets
deflecting a plurality of fibers along desired fiber orientation
angles .alpha. and .beta., fiber orientation angle .alpha. being
defined as the angle of fiber extension relative to horizontal,
fiber orientation angle .beta. being defined as the angle of fiber
extension relative to flow direction.
21. A method of increasing the life of a coalescer coalescing a
medium having two immiscible phases, namely a continuous phase and
a dispersed phase, said continuous phase flowing from upstream to
downstream, said coalescer comprising fibrous media capturing
droplets of said dispersed phase, coalescingly growing said
droplets into larger drops which further coalesce and grow to form
pools that drain, said coalescer having a pressure drop thereacross
increasing with time until the rate of drainage of said dispersed
phase equals the rate of capture, providing an equilibrium pressure
drop, said method comprising increasing coalescer life by reducing
dispersed phase saturation and increasing porosity by increasing
said rate of drainage.
22. The method according to claim 21 comprising providing said
fibrous media as a plurality of fibers and dominantly orienting
said fibers along a dominant fiber orientation angle .alpha. less
than 0.degree. and greater than or equal to minus 90.degree., where
.alpha. is defined as the angle of fiber extension relative to
horizontal.
23. The method according to claim 21 comprising providing said
fibrous media as a plurality of fibers and dominantly orienting
said fibers along a dominant orientation angle .beta. less than
60.degree. and greater than minus 60.degree., where .beta. is
defined as the angle of fiber extension relative to flow
direction.
24. The method according to claim 21 comprising vertically
vibrating said coalescer.
25. The method according to claim 21 comprising minimizing the
volume of said fibrous media where restriction is greatest and flow
rate least, and maximizing the volume of said fibrous media where
restriction is least and flow rate greatest, by providing said
coalescer with a lower region of greater dispersed phase saturation
and smaller volume than an upper region.
26. The method according to claim 21 comprising providing said
coalescer with a lower region of increased dispersed phase
saturation, and wicking said coalesced drops away from said fibrous
media at said lower region.
Description
BACKGROUND AND SUMMARY
[0001] The invention related to fibrous media coalescers.
[0002] Fibrous media coalescers are known in the prior art for
coalescing and separating a medium having two immiscible phases,
namely a continuous phase and a dispersed phase. For example: in
engine crankcase ventilation systems, and other air-oil separation
systems, the continuous phase is air, and the dispersed phase is
oil; in fuel-water separation systems, such as fuel filters, fuel
is the continuous phase, and water is the dispersed phase; in
water-oil separation systems, water is the continuous phase, and
oil is the dispersed phase. The invention is particularly well
suited for engine crankcase ventilation applications, but may be
used in other separation systems having immiscible fluids, e.g.
air-oil, fuel-water, water-oil, etc.
[0003] In designing a coalescer, trade-offs often need to be made.
For example, to increase efficiency by decreasing fiber diameter
and/or decreasing porosity and/or increasing thickness, the
trade-off may be higher pressure drop and/or shorter life and/or
larger package size. The present invention provides desirable
options for more favorable trade-offs, including lower pressure
drop.
BRIEF DESCRIPTION OF THE DRAWING
[0004] FIG. 1 schematically illustrates coalescence.
[0005] FIG. 2 is a graph showing loading and saturation.
[0006] FIG. 3 is a perspective view of a coalescer in accordance
with the invention.
[0007] FIG. 4 is a front elevation view of the coalescer of FIG. 3,
and shows a further embodiment.
[0008] FIG. 5. is like FIG. 4 and shows another embodiment.
[0009] FIG. 6 is like FIG. 4 and shows another embodiment.
[0010] FIG. 7 is like FIG. 4 and shows another embodiment.
[0011] FIG. 8 is like FIG. 4 and shows another embodiment.
[0012] FIG. 9 is like FIG. 4 and shows another embodiment.
[0013] FIG. 10 is like FIG. 4 and shows a further embodiment.
[0014] FIG. 11 is a schematic illustration showing fiber
orientation angle.
[0015] FIG. 12 is like FIG. 11 and shows another embodiment.
[0016] FIG. 13 is like FIG. 11 and shows another embodiment.
[0017] FIG. 14 is like FIG. 11 and shows another embodiment.
[0018] FIG. 15 is like FIG. 11 and shows another embodiment.
[0019] FIG. 16 is like FIG. 11 and shows another embodiment.
[0020] FIG. 17 is like FIG. 11 and shows another embodiment.
[0021] FIG. 18 is like FIG. 11 and shows another embodiment.
[0022] FIG. 19 is like FIG. 11 and shows another embodiment.
[0023] FIG. 20 is like FIG. 11 and shows another embodiment.
[0024] FIG. 21 is like FIG. 11 and shows another embodiment.
[0025] FIG. 22 is like FIG. 11 and shows another embodiment.
[0026] FIG. 23 is a microphotograph of fibrous media taken with a
scanning electron microscope at 43.times. magnification.
[0027] FIG. 24 is a microphotograph of fibrous media taken with a
scanning electron microscope at 35.times. magnification, at a
90.degree. orientation relative to FIG. 23.
[0028] FIG. 25 is a schematic illustration of a further embodiment
showing fiber orientation across a localized pocket.
DETAILED DESCRIPTION
[0029] FIG. 1 shows a coalescer 20 for coalescing a medium 22
having two immiscible phases, namely a continuous phase 24 and a
dispersed phase 26. For example, in the case of an engine crankcase
ventilation coalescer, the continuous phase 24 is air, and the
dispersed phase is oil, e.g. in the form of a fine mist having
droplets 26 of about one micron and smaller in diameter. The
continuous phase 24 flows from upstream to downstream, i.e. left to
right in FIG. 1. The coalescer includes fibrous media 28 capturing
droplets of the dispersed phase, coalescingly growing the droplets
into larger drops, for example as shown at 30, 32, which further
coalesce and grow to form pools such as 34 which drain as shown at
36. Within the gas or air stream 24, droplets 26 can collide and
grow in size by drop to drop coalescence. Upon entry into coalescer
20, the droplets are captured by impaction, interception,
diffusion, or electrostatic or other filtration mechanisms.
Droplets grow in size as captured and uncaptured droplets coalesce
to form larger drops. When the drops become large enough and pool
at 34 such that flow and/or gravitational forces exceed adhesion
forces, the enlarged/pooled drops flow through the bed of fibrous
media and are released as shown at 36. Dispersed phase saturation
varies within the coalescer, typically with increasing saturation
as one approaches the downstream face (right hand face FIG. 1), due
to viscous forces, and with increasing saturation at the bottom of
the coalescer due to gravity. Saturation, like porosity, is a
dimensionless number representing the fraction or percent of a
filter media's void space that is occupied by the captured
dispersed phase. Saturation does not mean that the entire void
volume is filled with the captured dispersed phase such as oil, but
rather that the element is holding as much oil as it can. At
saturation, more oil is held at the bottom and right than at the
top and left in FIG. 1.
[0030] In the absence of solid contaminants, the pressure drop
across a coalescer increases during the loading of the coalescer,
left side of FIG. 2, and then stabilizes once the coalescer becomes
saturated, right side of FIG. 2. FIG. 2 is a graphical plot of
pressure drop, .DELTA.P, in millimeters of water, verses time in
minutes. During loading, the rate of capture is greater than the
rate of drainage. During saturation, the rate of capture equals the
rate of drainage. In practice, plugging or excessively high
pressure occurs due to solid contaminants being captured and held
by the coalescer and/or the rate of capture exceeding the rate of
drainage from the coalescer. In two of the desirable aspects of the
present disclosure, the solids holding capacity of the coalescer is
increased and the rate of drainage of the coalescer is increased.
The noted saturation profile is important in coalescer design
because increased saturation corresponds to decreasing effective
porosity within the fibrous media bed and increasing
restriction.
[0031] The present disclosure provides a coalescer with fibrous
media adapted to reduce pressure drop thereacross by increasing
drainage therefrom. This is accomplished in various ways, to be
described.
[0032] FIG. 3 shows a fibrous media coalescer 40 having a hollow
interior 42 and providing inside-out flow, namely incoming flow as
shown at 44 into hollow interior 42, and then flow from hollow
interior 42 outwardly through fibrous media 46 as shown at arrows
48. Coalescer 40 has a first cross-sectional area A.sub.1 along a
first horizontal plane 50, and a second cross-sectional area
A.sub.2 along a second horizontal plane 52. Horizontal plane 52,
FIGS. 3, 4, is vertically below horizontal plane 50.
Cross-sectional area A.sub.2 is less than cross-sectional area
A.sub.1. Coalescer 40 has a perimeter 54 having a plurality of
chords thereacross, including vertical chords such as 56 and
horizontal chords such as 58. The longest of the chords, e.g. 56,
extends vertically. The horizontal chords include a first
horizontal chord, e.g. 58, along horizontal plane 50, and a second
horizontal chord 60 along horizontal plane 52. Horizontal chord 60
is shorter than horizontal chord 58. The drainage pressure on the
dispersed phase coalesced drops at the bottom of the coalescer, and
hence the drainage rate at such point, is a function of the height
of the dispersed phase column, which is proportional to the element
height and cross-sectional area. By providing the long dimension of
the shape along a vertical orientation, drainage pressure is
maximized. By having the cross-sectional area decrease towards the
bottom of the coalescer, two benefits are obtained. Firstly, the
volume of the element that is dispersed phase saturated is
minimized, where restriction is greatest and contaminated fluid
flow rate and removal are least. Conversely, the volume of the
element is maximized where restriction is least and contaminated
fluid flow rate and removal greatest. Secondly, a greater
proportion of element volume is available to capture and hold any
solids that may plug the coalescer or otherwise cause excessive
pressure drop. The lower section is more restrictive and has a
lower flow rate than the upper section, due to increased local
saturation relative to the upper section. One would expect removal
to also be higher in the lower section, however this is not the
case because: (a) since less flow goes through the lower section,
its contribution to total removal by the element is less; and (b)
the local velocity in the lower section is relatively high, which
in conjunction with the increased saturation, increases
re-entrainment of drops, which adversely affects removal.
[0033] FIGS. 3, 4, show the noted given shape in the vertical plane
as a hollow racetrack shape. Other given shapes in the vertical
plane are possible, for example a hollow oval shape 62, FIG. 5, a
hollow triangle shape 64, FIG. 6, a hollow square shape 66, FIG. 7,
a hollow trapezoid shape 68, FIG. 8, and a hollow circle shape 70,
FIG. 9. Inside-out flow is preferred because flow velocity
decreases with distance into the media, which minimizes possible
re-entrainment and carryover of coalesced drops into the clean side
and reduces the velocity in the portion of the coalescer where
saturation is high. This is a particular advantage for racetrack
and oval shapes because of their better space utilization due to
the smaller upstream open hollow space in the interior of elements
of these shapes. Outside-in flow is also possible.
[0034] In one embodiment, the fibrous media is provided by a
plurality of fibers having a nonrandom dominantly vertical
orientation, FIG. 4. The fibers are preferably polymeric and
preferentially oriented around the periphery of the given shape and
where possible parallel to the direction of gravity. The fibers
preferably extend dominantly circumferentially tangentially along
perimeter 54. The fibers preferentially extending dominantly
circumferentially tangentially along perimeter 54 are dominantly
vertical and provide increasing drainage pressure at lower regions
of the coalescer. The elements are preferably made by
electro-spinning or melt-blowing the fibers or wrapping or winding
sheets of fibrous media around the element periphery giving the
fibers the noted preferred orientation. The preferred orientation
and alignment of the fibers reduces the resistance of captured
drops to flow and enhances drainage by forming flow paths and
channels parallel to gravity. For ease of manufacturability,
polymeric fibers formed by melt-blowing or electro-spinning are
preferred, but other materials may also be used.
[0035] In a further embodiment, FIG. 4, vibration or oscillation of
the coalescer in a vertical direction, particularly in combination
with the above noted fiber orientation, is a further way to enhance
drainage, minimize restriction, and increase coalescer life. A
shaker 72 as shown in dashed line, which in one embodiment may be
an internal combustion engine or other mechanical component,
vibrates or oscillates the coalescer in a vertical direction. This
movement or vibration in the vertical direction accelerates the
captured drops, and the sudden reversal in direction causes them to
shear from the fibers and drain with minimum resistance. In the
noted implementation, the normal vibration of an engine or other
equipment facilitates such vibration, however it may be desirable
to provide judicious positioning and mounting of the coalescer or
by the addition of a mechanical vibrator for vibrating the
coalescer.
[0036] The coalescer has a lower region, e.g. at plane 52, FIG. 4,
of greater dispersed phase saturation and smaller volume than an
upper region, e.g. at plane 50, to minimize the volume of fibrous
media that is saturated with the dispersed phase where restriction
is greatest and continuous phase flow rate least and contaminant
removal least, and to maximize the volume of the fibrous media
where restriction is least and continuous phase flow rate greatest
and contaminant removal greatest. In a further embodiment, FIG. 10,
a lower media element 74 is provided of greater dispersed phase
wettability than fibrous media 46 and in contact with the lower
region of coalescer 40 and wicking coalesced drops from fibrous
media 46 at the lower region. In one embodiment, fibrous media 46
is non-wetting with respect to the dispersed phase, and lower media
element 74 is wetting with respect to the dispersed phase. In
preferred form, the cosine of the dispersed phase contact angle of
lower media element 74 is greater than the cosine of the dispersed
phase contact angle of fibrous media 46. In the above noted
internal combustion engine application, the purpose of wicking
layer 74 is to draw oil from the coalescer and direct it to a
collection vessel, such as the engine or a sump. In the preferred
form of such embodiment, wicking layer 74 is a non-woven filter
media, though alternatively it could be the walls of the sump
itself or other material with suitable wettability
characteristics.
[0037] The above disclosure provides various means for reducing
pressure drop across the coalescer, including enhancing drainage of
the coalesced dispersed phase from the coalescer. As shown in FIG.
2, the pressure drop across the coalescer increases with time until
the rate of drainage of the coalesced dispersed phase (e.g. oil in
the case of crankcase ventilation filters) equals the rate of
dispersed phase capture. The equilibrium pressure drop can be
reduced by increasing the drainage rate, which in turn reduces the
dispersed phase saturation of the coalescer and increases the
coalescer's effective porosity. By increasing the porosity, the
solids loading capacity of the coalescer is increased, as is
coalescer life.
[0038] Further to the above disclosed manner for increasing
drainage rate, various ways are available for taking further
advantage of fiber orientation. Fibers may be beneficially oriented
with respect to gravity and with respect to one another, as above
noted. For purposes herein, a first dominant fiber orientation
angle .alpha. is defined as the angle of fiber extension 76, FIGS.
11-22, relative to horizontal, i.e. relative to a direction which
is perpendicular to gravity. In FIGS. 11, 18, 20, .alpha. is
0.degree.. In FIGS. 12, 15, 21, .alpha. is minus 45.degree.. In
FIGS. 13, 16, 22, .alpha. is minus 90.degree.. In FIGS. 14, 17, 19,
.alpha. is 45.degree.. Fibers may also be beneficially oriented
with respect to the direction of flow. For purposes herein, a
second dominant fiber orientation angle .beta. is defined as the
angle of fiber extension 76 relative to flow direction 24. In FIGS.
11, 15, 19, .beta. is 0.degree.. In FIGS. 12, 16, 20, .beta. is
minus 45.degree.. In FIGS. 13, 17, 21, .beta. is minus 90.degree..
In FIGS. 14, 18, 22, .beta. is 45.degree.. FIGS. 11-22 show various
exemplary flow directions among the plurality of flow directions
from hollow interior 42 outwardly through fibrous media 46. FIGS.
11-14 show a flow direction 24 parallel to horizontal. FIGS. 15-18
show a flow direction 24 at minus 45.degree. relative to
horizontal. FIGS. 19-22 show a flow direction 24 at 45.degree.
relative to horizontal.
[0039] Three forces act on captured and coalesced drops, namely:
drag forces due to fluid flow; gravity; and adhesion or attachment
forces due to capillary pressure. The third force is controlled by
the wetting characteristics of the media and is noted above. Also
of significance is the interplay between drag and gravity forces.
Since it is desired to drain drops downwardly, it is desired that
fiber orientation angle a satisfy the condition that sine .alpha.
is less than zero, so that gravity assists drainage, for example
FIGS. 12, 13. If sine .alpha. is greater than zero, gravity hinders
drainage, increasing the equilibrium pressure drop, and reducing
life. Accordingly, the fiber orientation angles .alpha. in FIGS. 11
and 14 are less desirable. It is preferred that .alpha. be less
than 0.degree. and greater than or equal to minus 90.degree.. As to
fiber orientation angle .beta. relative to flow direction 24, drag
forces due to fluid flow decrease as cosine .beta. increases. It is
preferred that cosine .beta. be greater than 0.5, i.e. that .beta.
be less than 60.degree. and greater than minus 60.degree..
[0040] In order to decrease overall saturation of the coalescer,
reduce pressure drop, and increase life, it is not necessary for
all fibers to exhibit the preferred orientation. Rather, most of
the fibers should have the desired orientation, i.e. have a
dominant fiber orientation or angle. FIG. 23 is a microphotograph
showing dominant fiber orientation generally parallel to gravity
and perpendicular to flow direction, as shown by the indicated
arrows. FIG. 24 is a microphotograph showing fiber orientation
relative to gravity, wherein the direction of flow is into the
page. In further embodiments, sufficient numbers of fibers may be
provided having the desired orientation to enhance drainage
locally. Because the coalesced dispersed phase drains more freely
from such areas, the low local dispersed phase saturation and
pressure drop are maintained, and the net effective saturation of
the coalescer is reduced. While it is desirable for all fibers to
exhibit .alpha. less than 0.degree. and greater than or equal to
minus 90.degree. and .beta. less than 60.degree. and greater than
minus 60.degree., this may not be feasible. Various combinations
may also be employed. For example, in FIG. 25 if localized regions
of different fiber orientation are desired other than
perpendicular, localized pockets such as shown at 78 may be formed
in the fibrous media, such pockets deflecting a plurality of fibers
along other fiber orientation angles .alpha. and .beta.. These
localized pockets may be provided as shown in U.S. Pat. No.
6,387,144, incorporated herein by reference, for example by needle
punching to create such localized pockets, depressions, or
indentations with fiber orientation angles .alpha. and .beta.
different than 0.degree. and other than 90.degree. or minus
90.degree.. Other means may also be used for forming the localized
pockets, for example the media may be spiked with larger fibers,
wires, nails, brads, or similar structures having a high length to
width aspect ratio oriented such that .alpha. and/or .beta. is
other than 90.degree. or minus 90.degree. as desired. In another
alternative, a thread-like material may be sewed into the coalescer
media using a sewing machine or the like, with the threads being
oriented along an angle of 0.degree. (parallel to flow direction),
and the puncturing needle and thread would cause the surrounding
media fibers to orient at angles other than 90.degree. or minus
90.degree.. In another alternative, rather than needle punching,
the localized pockets could be created using a heated needle or an
ultrasonic welding type process. This will create a saturation
gradient causing the coalesced dispersed phase to drain from the
coalescer. Hence, even though all fibers do not have a desired
orientation angle .alpha. other than 0.degree., drainage will
nonetheless be enhanced compared to having all fibers oriented with
.alpha. equal to 0.degree.. These refinements introduce fibers or
structures preferentially oriented with respect to flow in a manner
that assists drainage and reduces pressure drop. Since it is often
impractical to have all fibers so oriented, localized pockets
having the preferred orientation can be created in layered media to
reduce pressure drop and improve coalescer life.
[0041] The present system provides a method of increasing the life
of a coalescer. The coalescer has a pressure drop thereacross
increasing with time until the rate of drainage of the coalesced
dispersed phase equals the rate of capture, providing an
equilibrium pressure drop. The method increases coalescer life by
reducing dispersed phase saturation and increasing porosity and
solids loading capacity by decreasing equilibrium pressure drop by
increasing the rate of drainage. The method involves providing
fibrous media as a plurality of fibers and dominantly orienting the
fibers preferably along a first dominant fiber orientation angle
.alpha. less than 0.degree. and greater than or equal to minus
90.degree. and preferably along a second dominant fiber orientation
angle .beta. less than 60.degree. and greater than minus
60.degree.. In one embodiment, the coalescer is vertically
vibrated. The method involves minimizing the volume of fibrous
media that is saturated with the dispersed phase where restriction
is greatest and flow rate and removal least, and maximizing the
volume of the fibrous media where restriction is least and flow
rate and removal greatest, by providing the coalescer with a lower
region of greater dispersed phase saturation and smaller volume
than an upper region. In one embodiment, the coalesced drops are
wicked away from the fibrous media at the lower region of increased
dispersed phase saturation.
[0042] It is recognized that various equivalents, alternatives and
modifications are possible within the scope of the appended
claims.
* * * * *